When performing communication between a helicopter and a terrestrial station via a communication satellite, the rotor blades of the helicopter intermittently block (instantaneously interrupt) the signal that is transmitted from the helicopter. Therefore, communication by a helicopter-mounted communication apparatus has lower efficiency than that in normal communication.
In order to deal with this kind of problem, a helicopter-mounted communication apparatus that is disclosed in Patent Literature 1 detects the rotation angle of the rotor blades, and then based on the detected rotation angle, changes the data compression and encoding parameters depending on the timing when the rotor blades cross the emission range of the antenna and the amount of accumulated transmission data, and stops transmission during the period that the rotor blades cross the emission range. As a result, the helicopter-mounted communication apparatus prevents a situation in which the rotor blades hinder communication.